American Academy of Professional Coders (AAPC) Practice Exam

Which of the following structures is NOT part of the largest organ system in the body?

1. Hair

2. Nails

3. Muscles

4. Skin

The correct answer is: Muscles

The largest organ system in the body is the integumentary system, which is primarily responsible for protecting the body from external damage, helping to regulate temperature, and providing sensory information. This system includes structures such as skin, hair, and nails. Muscles, while essential for movement and support, are not part of the integumentary system. Instead, they belong to the muscular system, which facilitates body movement through contractions. Thus, the correct answer identifies muscles as the structure that is not a part of the integumentary system, distinguishing it from the hair, nails, and skin, which are integral components of that system.